Scheduling method in a cellular system using wired relay station

ABSTRACT

A method, apparatus and computer product for scheduling in a cellular system using a wired RS is disclosed. In one aspect, a BS collects CQIs of all MSs within a cell, calculates a transmittable data amount for each of the MSs according to the CQI, selects an MS having a highest PF metric, and allocates resources to the selected MS.

CLAIM OF PRIORITY

This application claims the benefit of the earlier filing date, under 35U.S.C. §119(a), to that patent application filed in the KoreanIntellectual Property Office on Nov. 23, 2006 and assigned Serial No.2006-116356, the entire disclosure of which is hereby incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a scheduling and Radio ResourceManagement (RRM) technique in a cellular communication system. Moreparticularly, the present invention relates to a method for, increasingthe transmission throughput of a system by variably adjusting theboundaries among frame segments.

2. Description of the Related Art

Starting from the 1^(st) Generation (1G) analog mobile communicationsincluding Advanced Mobile Phone Service (AMPS), wireless communicationsystems have evolved from 2G digital mobile communications utilizingCode Division Multiple Access (CDMA) and Time Division Multiple Access(TDMA) to 3G multimedia mobile communications known as InternationalMobile Telecommunications-2000 (IMT-2000) to 4G. Since 3G, the evolutionhas focused on provisioning of services at high rate under a wide rangeof environments, meeting users' demands for a variety of wirelessmultimedia services beyond the traditional voice communication service.

One of critical technologies behind the evolution is efficientmanagement and distribution of frequency resources. In this context,active studies have been conducted on multi-hop transmission schemesbeyond single-hop schemes, which allow only direct transmission from aBase Station (BS) to a Mobile Station (MS) in a cell. A multi-hop relaysystem enables both relayed transmission from a BS to an MS via an RS(Relay Station) and direct transmission from a BS to an MS.

FIGS. 1A and 1B illustrate an exemplary configuration of a conventionalwireless RS multi-hop system.

FIG. 1A illustrates the configuration of a wireless RS multi-hop systemwith six wireless RSs. Referring to FIG. 1A, a cell 110 includes a BS111 and six wireless RSs 112-117. An MS 118 near to the BS 111 receivesa service from the BS 111, whereas an MS 119 at a cell boundary and thushaving a relatively low Signal-to-Interference and Noise Ratio (CINR)receives a service from the RS 112.

FIG. 1B illustrates subcells 1-6 covered by six wireless RSs 121-126within cell 127. The use of the RSs 121-126 effectively splits thesingle cell illustrated in FIG. 1A into seven cells. Because of the cellsplitting, the wireless RS multi-hop system can efficiently transmitdata to MSs which are located at the cell boundary or having a poorchannel status or in areas having many obstacles. Consequently, theservice area of the BS is expanded and shadow areas are substantiallyeliminated.

Compared to a conventional repeater system in which a repeaters are usedto amplify the received signal, and amplify even interference from anexternal cell as well, a wireless RS transmits only an intended signalto an MS and can perform scheduling/RRM for MSs within the subcellcovered by the RS in the wireless RS multi-hop system. In this manner,the use of wireless RSs enables data transmission to MSs in a shadowarea to which the BS cannot directly transmit data and increases cellcoverage and transmission throughput through additional scheduling/RRM.

While the wireless RS multi-hop system improves the reception SINRs ofMSs at the cell boundary, compared to the conventional single-hop systemor repeater system, it requires additional data transmission to relaydata. Because transmission from a BS to an RS also occupies radioresources, part of a transmission frame should always be spared for aBS-RS link. With this limitation, as more MSs request service, eachserving node (e.g. BS or RS) allocates less frequency resources at thesame time and repeated transmission causes a waste of time resources.Moreover, when data is delivered to an MS over a plurality of hops,resource distribution inefficiency is increased. The resulting decreasein effective channel resources available to MSs decreases transmissionthroughput.

The above problems may be averted by improved scheduling/RRM, use ofdirectional antennas, or frequency or time reuse. Nonetheless, thewireless RS multi-hop system has distinctive limitations in terms ofefficient resource utilization and especially transmission throughput.Because the channel status of links involved between a BS to an MS aredifferent, scheduling/RRM becomes very difficult and complex, if allchannels on the links are considered. Also, there will be a constrainton transmission of control signals in scheduling based on informationexchanged between each RS and a BS.

These limitations are caused by data transmission on a wireless linkbetween a BS and an RS and repeated transmission of the same resourcesfrom the BS to the RS. Hence, an RoF RS technology, i.e. a wired RSsystem is under study, which connects a BS to an RS by an optical fiberoffering excellent frequency characteristics and less data loss.

SUMMARY OF THE INVENTION

An aspect of exemplary embodiments of the present invention is toaddress at least the problems and/or disadvantages noted above and toprovide at least the advantages described below. Accordingly, an aspectof exemplary embodiments of the present invention is to provide a methodfor increasing transmission throughput in a wired RS system.

Another aspect of exemplary embodiments of the present invention is toprovide a method for increasing transmission throughput in a wired RSmulti-hop system using a resource reuse scheme.

In accordance with an aspect of exemplary embodiments of the presentinvention, there is provided a scheduling method in a cellular systemusing a wired RS, in which a BS collects CQIs (Channel QualityInformation) of all MSs within a cell, calculates a transmittable dataamount for each of the MSs according to the CQI, selects an MS having ahighest PF (Proportional Fairness) metric, and allocates resources tothe selected MS.

BRIEF DESCRIPTION OF THE DRAWINGS

The above features and advantages of certain exemplary embodiments ofthe present invention will be more apparent from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIGS. 1A and 1B illustrate an exemplary configuration of a conventionalmulti-hop relay cellular system using wireless RSs;

FIGS. 2A and 2B illustrate the configuration of a wired RS cellularsystem, to which the present invention is applied;

FIGS. 3A and 3B illustrate resource allocation based on time reuse inthe wired RS cellular system according to an exemplary embodiment of thepresent invention;

FIG. 4 is a flowchart illustrating a scheduling method in the wired RScellular system according to an exemplary embodiment of the presentinvention;

FIGS. 5A to 5D illustrate resource allocations based on time reuse inthe wired RS cellular system according to an exemplary embodiment of thepresent invention; and

FIG. 6 is a graph illustrating simulation results of the schedulingmethod in the wired RS cellular system according to an exemplaryembodiment of the present invention.

Throughout the drawings, the same drawing reference numerals will beunderstood to refer to the same elements, features and structures.

DETAILED DESCRIPTION OF THE INVENTION

The matters defined in the description such as a detailed constructionand elements are provided to assist in a comprehensive understanding ofexemplary embodiments of the invention. Accordingly, those of ordinaryskill in the art will recognize that various changes and modificationsof the embodiments described herein can be made without departing fromthe scope and spirit of the invention. For the purposes of clarity andsimplicity, descriptions of well-known functions and constructions areomitted for clarity and conciseness.

FIGS. 2A and 2B illustrate the configuration of a wired RS cellularsystem to which the present invention is applied.

In FIGS. 2A and 2B, the wired RS system has a network configurationsimilar to that of a wireless RS multi-hop system. FIG. 2A illustrates awired RS system with six RSs. Referring to FIG. 2A, the wired RS systemis similar to the wireless RS system illustrated in FIG. 1A in that asingle cell 210 includes one BS 211 and six RSs 212-217 and they differin that BS-RS links are formed by optical fibers 220 in the wired RSsystem. Despite additional cost for installing optical fibers betweenthe BS and the RSs and fixedness of the RSs, the wired RS system offersthe following benefits.

First, the wired RS system experiences only minimal signal attenuationon the BS-RS links owing to the use of optical fibers. Another benefitis that as radio resources are saved compared to the wireless RS system,many users can further be allocated resources. Further, since morecontrol signals can be transmitted due to the radio resource saving,various intelligent scheduling techniques are viable. Compared to thewireless RS system, a variety of multi-hop networks can be designed.

Consequently, the transmission throughput of individual users and theentire cell is increased. Each RS acts as a small BS. Thus, as an idealtransmission throughput increases in proportion to the number of RSs perhop, hardware cost decreases gradually, and frequency resource costincreases continually, the wired RS system will eventually outperformthe wireless RS system.

If every node uses the same frequency or time resources in a cellularsystem, MSs are affected by intra-cell interference and inter-cellinterference from nodes using the same resources as those of theirserving nodes and thus suffer from a decrease in reception SINRs. Toreduce the interference and increase resource efficiency, a cell usesresources which are the same as those of a remote cell and differentfrom those of a neighbor cell. This is called frequency reuse or timereuse. The frequency reuse or time reuse is also applicable to the wiredRS system in a similar manner.

FIG. 2B illustrates a frequency reuse with a frequency reuse factor of 7in a wired RS system with the same RS layout as illustrated in FIG. 2A.A BS 220 and RSs 221-226 within subcells transmit data in seven resourcesegments of a frame according to a time reuse scheme, as illustrated inFIG. 3A. Specifically, the BS allocates resources to MSs that it servesand transmits data to them in resource segment 0 defined on a time axis,and discontinues the transmission in resource segment 1. At the sametime, RS1 starts transmission in resource segment 1. In the same manner,RS2 to RS6 transmit data in corresponding resource segments 2 to 6,respectively. According to the time reuse scheme, each node shouldcomplete its transmission during a predetermined time period, therebyavoiding intra-cell/inter-cell interference. However, the reuse factorand the transmission throughput are in a trade-off relationship and thefixed resource segments for the nodes as illustrated in FIG. 3A are noteffective in flexibly coping with different traffic requirements of MSswithin the subcells.

The above frame resource division method is referred to as “static framedivision” and problems encountered with the static frame division willbe described below.

For example, if MSs within subcells 0, 4 and 5 request Near Real TimeVideo (NRTV) data, MSs within subcells 2 and 6 request Voice overInternet Protocol (VoIP) data, and MSs within subcells 1 and 3 requestHypertext Transfer Protocol (HTTP) data, which is a situation that MSswithin a cell are concentrated around a particular node or a particularnode requests a larger amount of traffic, relatively more traffic shouldbe allocated to the NRTV data during a given transmission period becausea high data rate should be ensured for the NRTV data in real time.However, the data transmission is discontinued in the next resourcesegment in the static frame division illustrated in FIG. 3A. As aresult, a required minimum data rate is not satisfied during ascheduling time or a transmission frame period, and thus Quality ofService (QoS) is not guaranteed. On the other hand, excess resources areallocated to subcells 2 and 6 with the VoIP data and subcells 1 and 3with the HTTP data. The static frame division does not reflect varioustraffic characteristics. Therefore, as illustrated in FIG. 3B, framesegments 0, 4 and 5 are expanded, while the other frame segments aremade smaller, to thereby actively cope with the above-describeddifferent traffic situations.

In contrast to the static frame division, dividing a frame variablyaccording to a data transmission environment is called “dynamic framedivision”. A BS and each RS perform scheduling and RRM independently inthe static frame division scheme, whereas a BS collects informationabout the channel status of MSs covered by RSs from the RSs and performsscheduling/RRM for them in the dynamic frame division scheme.

Scheduling is very crucial to maximization of transmission throughputand system efficiency, while satisfying QoS requirements from users andproviding fairness among MSs. The scheduling is an algorithm thatdetermines time to allocate resources, frequency resources to beallocated, and the MSs to be allocated the resources. In the wired RSmulti-hop system, nodes allocate resources in a transmission frame byvarious scheduling algorithms.

Regarding a Proportional Fairness (PF) scheduling according to thepresent invention, it is one of opportunistic scheduling techniques thatselect an optimal user under various conditions such as QoS or channelinformation, seeking to maximize multiple user gains. If there are datato be transmitted to a plurality of users in a cell, a PF schedulercollects information about the channel status of the users anddetermines a maxim transmittable data amount for each user according tothe channel status information. Then the PF scheduler calculates theratio of an available maximum instantaneous data rate to an average datarate or a PF priority metric for every user. This value is a schedulingpriority level and a user having the highest priority level is selectedto receive data in a current time slot. Also, the PF scheduling isperformed in parallel for each frequency band, for resource allocation.

$\begin{matrix}{{P\; F\mspace{14mu}{metric}\mspace{14mu}{for}\mspace{14mu}{ith}\mspace{14mu} M\; S} = \frac{R_{i}(t)}{\overset{\_}{R_{i}(t)}}} & (1)\end{matrix}$

-   -   where i denotes the index of an MS and        -   R_(i)(t) denotes a data rate available to the i^(th) MS in a            scheduling time period t. R_(i)(t) is calculated based on            the Channel Quality Information (CQI) of a previous frame,            such as average Carrier-to-Interference and Noise Ratio            (CINR), which the MS feeds back to its serving node.        -   R_(i)(t) denotes the average data rate of data transmitted            to the i^(th) MS from a previous time period to the            scheduling time period t. The ratio between these two            factors is the priority function of the i^(th) MS. The PF            scheduler calculates a PF metric for every MS, selects an MS            with the largest PF metric by Equation (2), and allocates            resources to the selected MS in the scheduling time period            t.

$\begin{matrix}{i^{*} = {\arg\mspace{11mu}\max\left\{ \frac{R_{i}(t)}{\overset{\_}{R_{i}(t)}} \right\}}} & (2)\end{matrix}$

-   -   where i* denotes the selected MS in the scheduling time period        t.

According to Equation (1) and Equation (2), the average data rateR_(i)(t) becomes higher for an MS that has a high CQI and thus receivesa relatively large amount of data in a prior time period. Thereafter,the PF metric of the MS decreases over time, which in turn decreases thepriority level of the MS. Then, the MS has fewer opportunities ofresource allocation. On the other hand, for an MS with a relatively lowCQI, the average data rate R_(i)(t) becomes lower. Therefore, the PFmetric of the MS increases over time, which in turn increases thepriority level of the MS. Then, the MS has more opportunities ofresource allocation.

In this manner, the PF metric leads to allocation of time and frequencyresources offering a maximal transmission throughput, taking intoaccount the channel status of each MS. Therefore, although the PFscheduling is inferior to Round Robin (R/R) scheduling in terms ofabsolute fairness, it can increase transmission throughput because ofits fairness in CQI. After selecting the MS for the scheduling timeperiod t and allocating resources to the selected MS in the abovemanner, R_(i)(t) is updated for the scheduling time period t by weightedaveraging according to Equation (3).

$\begin{matrix}\begin{matrix}{\overset{\_}{R_{i}(t)} = {{\left( {1 - \frac{1}{t_{c}}} \right){R_{i}\left( {t - 1} \right)}} + {\frac{1}{t_{c}}{R_{i}\left( {t - 1} \right)}}}} & {{{for}\mspace{14mu} i} = i^{*}} \\{\overset{\_}{R_{i}(t)} = {\left( {1 - \frac{1}{t_{c}}} \right){R_{i}\left( {t - 1} \right)}}} & {{{for}\mspace{14mu} i} \neq i^{*}}\end{matrix} & (3)\end{matrix}$

If resources were allocated to the i^(th) MS in a previous schedulingtime period (t−1), R_(i)(t) is updated for the scheduling time period tby the upper formula in Equation (3) and if resources were not allocatedto the i^(th) MS for the scheduling time period (t−1), R_(i)(t) isupdated for the scheduling time period t by the lower formula inEquation (3). A weight t_(c) is set to a maximum time period for whichthe MS is not serviced. As t_(c) becomes smaller, weights, being thecoefficients of the terms in Equation (3), get larger. In this case, thePF scheduling becomes similar to the R/R scheduling that sequentiallyallocates resources of the same size.

FIG. 4 is a flowchart illustrating a scheduling method in the wired RScellular system according to an exemplary embodiment of the presentinvention.

Referring to FIG. 4, it is assumed that a serving node (BS or RS) hasbeen determined for each MS before scheduling. Nodes using the sameresource segment are called a reuse group so that the schedulingoperation is applicable for a reuse factor of 3 (illustrated in FIG. 5A)as well as for a reuse factor of 7 (illustrated in FIG. 2B). It is alsoassumed that a cell has k RSs and (k+1) nodes inclusive of a BS, N reusegroups are formed, including the BS, and a time reuse scheme is adoptedas illustrated in FIG. 3A. A transmission frame has C resources and thenumber of resources allocated to a frame for a k^(th) node is R_(k).

In step 411, MSs feed back their CQIs to the BS and all RSs, i.e. theirserving nodes, and the BS receives the CQIs via the RSs, thus collectingall CQIs within the cell. The BS selects MSs to be scheduled in step 413and calculates the numerator R_(i)(t) of Equation (1). That is, atransmittable data amount for every selected MS in step 415 andcalculates an average data rate R_(i)(t) and a PF metric for everyselected MS in step 417. In step 419, the BS selects an MS with thehighest PF metric by Equation (2).

Steps 415, 417 and 419 are performed for PF scheduling. The selected MSis an MS with the highest PF metric not in a subcell but in the entirecell. If the PF scheduling is performed on a frequency band-by-frequencyband basis, i.e. the PF scheduling is performed in parallel, as many MSsare selected for resource allocation with respect to the frequency bandsat one scheduling.

In step 421, the BS allocates resources to a frame for the serving nodeof the selected MS (scheduling is performed for every MS in the cell).If resources are reused, steps 421 and 423 are performed simultaneously.In step 423, the BS counts the number of resources allocated to theframe of each node and proceeds to step 425.

The BS detects one node having the most allocated resources from eachreuse group for a current scheduling time and compares the sum ofresources allocated to the detected nodes with the total number C ofresources per transmission frame in step 425. If the sum is not equal toC, the resource allocation is repeated until they equal. If the sum isequal to C, the BS determines boundaries among frame segments accordingto the sizes of the allocated resources in step 427.

If there are resources unused for each node in step 429, the BSallocates the resources to the frame segments determined in step 427 andcompletes the scheduling. Each node transmits the resource-allocatedframe, thus finishing one cycle. Then the above operation is repeated.

As the operation is repeated, the CQIs of the MSs change everyscheduling time and the traffic requirement of each MS changes.Therefore, the frame segments vary dynamically.

FIGS. 5B and 5C illustrate examples of static frame division and dynamicframe division for a wired RS system with a subcell configurationillustrated in FIG. 5A. Here, resources are divided in time. The dynamicframe division of the present invention is applicable to frequencyresources as well as time resources. In FIG. 5D, the scheduling of thepresent invention is performed in parallel for respective frequencybands and thus two dimensional time-frequency resources areframe-divided.

FIG. 6 illustrates improved transmission throughput when the schedulingof the present invention is used in a wired RS multi-hop system. Asimulation was performed under the following conditions.

Cell structure: hexa cells (1 BS and 6 RSs)

Number of simulation occurrences: 50000

Traffic model: full queue model

Number of MSs: 120

Reuse factor: 3/4/7

Channel model: Rayleigh fading

Interference model: interference from nodes using the same resources insix neighbor cells is considered.

Path loss model: Lee's model

Scheduling: scheduling based on BS-centralized dynamic fame division ofthe present invention.

Referring to FIG. 6, the BS-centralized scheduling scheme of the presentinvention increases transmission throughput by 6.8%, 16.3%, and 22.3%respectively for reuse factors of 3, 4 and 7, compared to the staticframe division The performance increases with the reuse factor accordingto the present invention.

In accordance with the present invention, a frame is dynamically dividedby centralized scheduling based on an PF metric that reflects thechannel status of all MSs within a cell in a wired RS cellular system.Since scheduling is performed, taking into account traffic situationsand channel information, transmission throughput is increased.

The above-described methods according to the present invention can berealized in hardware or as software or computer code that can be storedin a recording medium such as a CD ROM, an RAM, a floppy disk, a harddisk, or a magneto-optical disk or downloaded over a network, so thatthe methods described herein can be rendered in such software using ageneral purpose compute (e.g, Pentium processor), or a special processoror in programmable or dedicated hardware, such as an ASIC or FPGA. Aswould be understood in the art, the computer, the processor or theprogrammable hardware include memory components, e.g., RAM, ROM, Flash,etc. that may store or receive software or computer code that whenaccessed and executed by the computer, processor or hardware implementthe processing methods described herein.

While the invention has been shown and described with reference tocertain exemplary embodiments of the present invention thereof, it willbe understood by those skilled in the art that various changes in formand details may be made therein without departing from the spirit andscope of the present invention as defined by the appended claims andtheir equivalents.

1. A scheduling method of a Base Station (BS) in a cellular system usinga wired Relay Station (RS), comprising: collecting by the base stationChannel Quality Information (CQIs) of all Mobile Stations (MSs) within acell of a plurality of cells and the BS receiving CQIs via at least onerespective wired RS per cell that is wired to the BS and receives datain resource segments of a frame, and each of said at least onerespective wired RS per cell communicates wirelessly with the MSs withina respective cell of the plurality of cells; calculating a transmittabledata amount for each of the MSs according to the CQIs; and selecting anMS having a highest PF metric and allocating resources to the selectedMS, the PF metric being defined as: $\begin{matrix}{{{PF}\mspace{14mu}{metric}\mspace{14mu}{for}\mspace{14mu}{ith}\mspace{14mu}\underset{.}{M}S} = \frac{R_{i}(t)}{R_{i}(t)}} & (4)\end{matrix}$ where i denotes the index of an MS, R_(i)(t) denotes adata rate available to an i^(th) MS in a scheduling time period t, andR_(i)(t) denotes the average data rate of data transmitted to the i^(th)MS from a previous time period to the scheduling time period t: and theMS having the highest PF metric being expressed as: $\begin{matrix}{i^{*} = {\arg\mspace{14mu}\max\left\{ \frac{R_{i}(t)}{R_{i}(t)} \right\}}} & (5)\end{matrix}$ where i* denotes the selected MS in the scheduling timeperiod t; and wherein the RS is wired to the BS via optical fiber. 2.The method of claim 1, further comprising: updating R_(i)(t) whenselecting MSs to be scheduled and allocating resources for thescheduling time period t as: $\begin{matrix}\begin{matrix}{\overset{\_}{R_{i}(t)} = {{\left( {1 - \frac{1}{t_{c}}} \right){R_{i}\left( {t - 1} \right)}} + {\frac{1}{t_{c}}{R_{i}\left( {t - 1} \right)}}}} & {{{for}\mspace{14mu} i} = i^{*}} \\{\overset{\_}{R_{i}(t)} = {\left( {1 - \frac{1}{t_{c}}} \right){R_{i}\left( {t - 1} \right)}}} & {{{for}\mspace{14mu} i} \neq i^{*}}\end{matrix} & (6)\end{matrix}$ where t_(c) is set to a maximum time period for which thei^(th) MS is not serviced.
 3. The method of claim 1, further comprising:dynamically dividing a frame by counting the number of resource segmentsallocated to a frame of each node being the BS or an RS.
 4. The methodof claim 3, wherein the dynamic frame division comprises: detecting onenode having the most allocated resources for a current scheduling timeperiod from each reuse group; comparing a sum of resources allocated todetected nodes with the total number of resources per transmissionframe; and determining boundaries among frame resource segmentsaccording to the sizes of the allocated resources if the sum is equal tothe total number of resources per transmission frame.
 5. The method ofclaim 3, wherein the dynamic frame division comprises: dividingtwo-dimensional time and frequency resources of the frame.
 6. Anapparatus for scheduling of a Base Station (BS) in a cellular systemusing a wired Relay Station (RS), comprising: a processor incommunication with a memory, the memory storing software instructionwhich when accessed by the processor causes the processor to execute:collecting by the Base Station Channel Quality Information (CQIs) of allMobile Stations (MSs) within a cell of a plurality of cells and the BSreceiving CQIs via at least one respective wired RS per cell that iswired to the BS and receives data in resource segments of a frame, andeach of said at least one respective wired RS per cell communicateswirelessly with the MSs within a respective cell of the plurality ofcells; calculating a transmittable data amount for each of the MSsaccording to the CQIs; and selecting an MS having a highest PF metricand allocating resources to the selected MS, the PF metric being definedas: $\begin{matrix}{{P\; F\mspace{14mu}{metric}\mspace{14mu}{for}\mspace{14mu}{ith}\mspace{14mu} M\; S} = \frac{R_{i}(t)}{\overset{\_}{R_{i}(t)}}} & (4)\end{matrix}$ where i denotes the index of an MS, R_(i)(t) denotes adata rate available to an i^(th) MS in a scheduling time period t, andR_(i)(t) denotes the average data rate of data transmitted to the i^(th)MS from a previous time period to the scheduling time period t; and theMS having the highest PF metric being expressed as: $\begin{matrix}{i^{*} = {\arg\mspace{11mu}\max\left\{ \frac{R_{i}(t)}{\overset{\_}{R_{i}(t)}} \right\}}} & (5)\end{matrix}$ where i* denotes the selected MS in the scheduling timeperiod t; and wherein the RS is wired to the BS via optical fiber. 7.The apparatus of claim 6, wherein the software instruction furthercausing the process to execute: updating R_(i)(t) when selecting MSs tobe scheduled and allocating resources for the scheduling time period tas: $\begin{matrix}\begin{matrix}{\overset{\_}{R_{i}(t)} = {{\left( {1 - \frac{1}{t_{c}}} \right){R_{i}\left( {t - 1} \right)}} + {\frac{1}{t_{c}}{R_{i}\left( {t - 1} \right)}}}} & {{{for}\mspace{14mu} i} = i^{*}} \\{\overset{\_}{R_{i}(t)} = {\left( {1 - \frac{1}{t_{c}}} \right){R_{i}\left( {t - 1} \right)}}} & {{{for}\mspace{14mu} i} \neq i^{*}}\end{matrix} & (6)\end{matrix}$ where t_(c) is set to a maximum time period for which thei^(th) MS is not serviced.
 8. The apparatus of claim 6, wherein thesoftware instruction further causing the process to execute: dynamicallydividing a frame by counting the number of resource segments allocatedto a frame of each node being the BS or an RS.
 9. The apparatus of claim8, wherein the dynamic frame division comprises: detecting one nodehaving the most allocated resources for a current scheduling time periodfrom each reuse group; comparing the sum of resources allocated todetected nodes with the total number of resources per transmissionframe; and determining boundaries among frame resource segmentsaccording to the sizes of the allocated resources if the sum is equal tothe total number of resources per transmission frame.
 10. The apparatusof claim 8, wherein the dynamic frame division comprises: dividingtwo-dimensional time and frequency resources of the frame.
 11. Themethod of claim 1, wherein said mobile stations transmit CQI informationin a designated time slot.
 12. The apparatus of claim 6, wherein saidmobile stations transmit CQI information in a designated time slot. 13.The computer product of claim 1, wherein said mobile stations transmitCQI information in a designated time slot.
 14. The method of claim 1,wherein R_(i)(t) is calculated based on the Channel Quality Information(CQI) of a previous frame, said CQI represented as averageCarrier-to-Interference and Noise Ratio (CINR).
 15. The apparatus ofclaim 1, wherein R_(i)(t) is calculated based on the Channel QualityInformation (CQI) of a previous frame, said CQI represented as averageCarrier-to-Interference and Noise Ratio (CINR).
 16. The product of claim1, wherein R_(i)(t) is calculated based on the Channel QualityInformation (CQI) of a previous frame, said CQI represented as averageCarrier-to-Interference and Noise Ratio (CINR).